Hydrocarbon sources for the carbon nanotubes production by chemical vapour deposition: a review

The synthesis of carbon nanotubes (CNTs) using a chemical vapour deposition (CVD) method requires the use of hydrocarbon as the carbon precursor. Among the commonly used hydrocarbons are methane and acetylene, which are both light gas-phase substances. Besides that, other carbon-rich sources, such as carbon monoxide and coal, have also been reportedly used. Nowadays, researches have also been conducted into utilising heavier hydrocarbons and petrochemical products for the production of CNTs, such as kerosene and diesel oil. Therefore, this article reviews the different kind of hydrocarbon sources for CNTs production using a CVD method. The method is used for it allows the decomposition of the carbon-rich source with the aid of a catalyst at a temperature in the range 600-1200°C. This synthesis technique gives an advantage as a high yield and high-quality CNTs can be produced at a relatively low cost process. As compared to other processes for CNTs production such as arc discharge and laser ablation, they may produce high quality CNTs but has a disadvantage for use as large scale synthesis routes

Synthesis and Biological Activity Study of Co and Cr Complexes with α-(2-Salsayl)-<i>N</i>-phenyl Nitrone and Oxide Nanoparticles

This paper describes the synthesis of two complexes from the ligand α-(2-Salsayl)-N-phenyl nitrone with CoCl2 and CrCl2. The ligand was characterized by several spectroscopic techniques (ultraviolet/visible (UV/Vis), nuclear magnetic resonance (1H-NMR and 13C-NMR), Fourier-transform infrared spectroscopy (FTIR), and mass spectrometry (MS). While infrared, ultraviolet-visible (UV-Vis), thermal analysis, and job method studies were used to reveal the structure of the complexes. The synthesized complexes were then synthesized by the sonochemical method, and the copper and chromium oxide nanoparticles were produced using the thermal decomposition method. Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) characterization confirmed the formation of Co3O4 and Cr2O3 nanoparticles. Antimicrobial studies of the complexes against some microorganisms, such as Staphylococcus epidermis and Escherichia coli, utilizing the disk diffusion method, revealed the antibacterial activity of the complexes

Synthesis and morphological study of graphenated carbon nanotube aerogel from grapeseed oil

Grapeseed oil as a new source of graphenated carbon nanotube (g-CNTs) hybrids was described in this paper. Mesoporous three-dimensional (3D) g-CNT aerogel was synthesized by a floating catalyst chemical vapor deposition (FCCVD) method. The effect of the H2 gas ratio was evaluated, and the graphenated g-CNTs morphology was identified by various physico-chemical techniques, such as field-emission scanning microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, thermogravimetric analysis (TGA), and N2 sorption studies. Furthermore, the multi-wall carbon nanotube (MWCNT) bundles in the network were highly disordered and rounded by graphene foliate structures in which a large number of sharp edges of graphene sheets were found

Synthesis and characterization of carbon nanotube aerogel from waste engine oil via floating catalyst chemical vapor deposition for oil spill removal

Carbon nanotube (CNT) aerogel is a novel nanomaterial with three-dimensional (3D) macrostructure. The long CNTs assemble display high porosity, spinnability, structural stability, and good electrical conductivity. These characteristic represents a critical approach towards practical applications such as supercapacitors, gas storage, catalyst support, filtration, separation, biological sensors and oil spill removal. CNT aerogel is directly synthesized by floating catalyst chemical vapor deposition (FCCVD) using petrochemicals such as methane, cyclohexane, toluene or dichlorobenzene as a carbon source. Nevertheless, the high cost, depletion of the petrochemical products, and environmental aspects have brought the consideration of using waste engine oil (WEO) instead as a carbon source. This work is the first ever attempt to utilize WEO for CNT aerogel production. It was done via catalytic decomposition of WEO with ferrocene as a catalyst through FCCVD method. Prior to the reaction process, WEO was first filtered to remove dirt and any solid particles that might present. This was later followed by fractional distillation of the oil into different fractions which resulted in five (5) fractions. Gas chromatography-mass spectrometry (GC-MS) showed successful separation of low molecular weight hydrocarbons which was necessary for dissolving the catalyst, while Carbon-nitrogen-sulfur (CNS) analysis indicated that each fraction has more than 69% carbon, less than 0.2% nitrogen and less than 0.09% sulfur. The reaction was carried out at 1150 °C and 1200 °C in hydrogen with a flowing rate of 550 - 650 mL min-1. The carbon source solution (10 mL) was continuously injected into the furnace tube at a feeding rate of 10 mL h- 1 during one hour reaction time. It was found that all the synthesized CNT aerogel were multi-walled carbon nanotubes (MWCNTs) with 99.14% yield for CNT aerogel 3 synthesized at 1150 °C. Interestingly, CNT aerogel 2-2 and CNT aerogel 3-2 revealed graphenated carbon nanotubes (G-CNTs) structure obtained at reaction temperature 1200 °C. The CNT aerogels had a mesopore distribution with specific surface area in the range between 80.6 - 222.0 m2 g-1. Field emission scanning electron microscopy (FESEM) revealed randomly orientated to entangle thin multi-walled structure. Oil spill removal study was done by conducting benzene, toluene, and mxylene (BTX) as well as kerosene, diesel oil, palm oil and waste engine oil absorption of the synthesized CNTs. Results showed that CNT aerogel 5-2 gave the highest sorption capacity (Qe) for kerosene in both oil and oil/water system at 71.43 and 75.19 (g g-1), respectively. Absorption capacity was sustained at 90% for benzene, toluene, and m-xylene, 93% for kerosene, 87% for diesel fuel, 68% for palm oil, and 65% for waste engine oil even after 10 absorption cycles. Therefore, it can be concluded that CNT aerogel were successfully prepared from WEO by using FCCVD method which produced MWCNT at 1150 °C and graphenated CNT aerogel at 1200 °C. The CNT aerogel showed an excellent sorption capacity for all tested solvents and oils in both oil and oil/water systems with commendable recycle performance

Direct synthesis of carbon nanotube aerogel using floating catalyst chemical vapor deposition: effect of gas flow rate

Carbon nanotube aerogel (CNT aerogel) was synthesized through the catalytic decomposition of toluene in the mixture of ferrocene and thiophene through floating catalyst chemical vapor deposition method. This study described the effect of (Ar and H2) carrier gas flow rate on the quality and yield of CNT aerogel. Results indicated that the flow rate of the gas was an important parameter which helped in determining the yield and quality of the CNTs. The CNTs are multiwalled with its diameter decreased when the H2 flow rate was increased. Scanning electron microscopy indicated the average diameter of ≈ 31, 30, 27, 26, 18, and 15 nm when the H2 flow rate was increased from 400, 450, 500, 550, 600, 650 sccm, respectively. Furthermore, elemental analysis with energy dispersion spectrum for CNT aerogel produced at 600 sccm resulted in a 96.22 wt% carbons along with 3.78 wt% iron in the CNT aerogel sample. Results indicated that a hydrogen flow rate of 600 sccm produced high yield and good CNTs morphology